1. Field of the Invention
The invention relates generally to a lightweight tension structure having a unique T-shaped center pole, and in particular, to a pavilion type tent structure having flexible fabric membranes in tension between peripheral arches such that the tension on the membrane may be maintained and adjusted by positioning the T-shaped center pole in a pocket formed in the flexible fabric membrane.
2. Summary of the Related Art
Fabric structures and enclosures are used in a variety of applications. Large fabric domes cover outdoor arenas, shopping malls, swimming pools, tennis courts and other locations having a need for a customized shelter. Specially designed fabric structures may be temporarily or permanently used for fairs, meeting halls, pavilions, barracks, and other similar applications. Smaller tents provide camping and residential shelters.
Fabric structures are also used extensively for commercial awnings and canopies to provide both shelter and promotional benefits to a business entity. In addition to the more traditional uses noted above, fabric structures may also be used for sculptures and other more artistic purposes.
In fabric structures, the proper tension must be maintained on the fabric to accommodate the intended application of such fabric structure. A number of different support structures and tensioning means have been developed to maintain the desired tension in a fabric structure. Most of the smaller or mid-sized fabric structures utilize a center support means with anchored guide lines attached to side supports in order to maintain the structure.
In many fabric structures, it is desirable to reinforce or eliminate the hole and bail ring formed in the membrane for acceptance of a center pole in "point pole" construction. A number of different panels are typically joined at the bail ring, which makes the joint one of the most difficult processes from a manufacturing standpoint and one of the weakest points from a quality perspective. In an effort to minimize fabric overlapping and more easily distribute the tensional forces over the entire membrane, tent manufacturers have been looking for a means to eliminate the bail ring in certain applications.
In U.S. Pat. No. 3,886,961 to Geiger et al, a portable structure utilizes the cooperation of flexible arches as compression members in the structure. The tensioned membrane is provided with stressed cables to brace the arches and form a rigid structure.
U.S. Pat. Nos. 3,909,993 and 4,092,992 to Huddle show additional structures using arched supports and means for making laminated arch members. The supports are forced apart in the crown area of the arch by the use of inclined arches or other tensioning means to support the structure.
A building structure including one polyhyparic surface formed of a continuous tensioned web coupled to structural members along its periphery is disclosed in U.S. Pat. No. 4,584,800 to Burt et al.
U.S. Pat. No. 4,644,706 Stafford et al. teaches a building structure with a transversely tensioned fabric covering. A plurality of arches supported in spaced, vertical positions. A winch is used to tension the corresponding fabric panels.
U.S. Pat. No. 4,880,024 to Brell shows a self supporting tent structure designed primarily for protecting small aircraft. The tent structure includes a special tensioning device to obtain the desired tension on the roof of the tent.
U.S. Pat. No. 4,886,084 to Lawrence et al. shows a panelized fabric-covered structure with removable and replaceable fabric panels, including an expandable frame having a plurality of frame members for holding a fabric panel.
U.S. Pat. No. 4,945,936 shows an umbrella type tent with a collapsible frame. An upper and lower clevis is used to provide a flexible upper section which can conform to the dome of the sheet material forming the tent cover.
A unique apex member is provided for the tent structure in U.S. Pat. No. 4,966,178 to Eichorn. The apex member is secured to each of the tent poles and includes a tensioning member which is moved to a tension position for providing the necessary tension to the tent structure.